A good portion of the world hears the word tuberculosis and thinks of the bacterial infection that plagued those of the past. In campaigns for better living standards, antibiotics and vaccines it appeared that tuberculosis is under control since the 20<sup>th</sup> century. While it seemed promising, new evidence is proving that tuberculosis is capable of outsmarting humans and its attack on the human body.
The tuberculosis bacterium attacks the lungs and in some cases other organs of its human hosts. Scientists have found that certain strains work against the immune system while others work with the immune system. In strains that work against the immune system, the bacteria moves into the lungs and the immune system builds a wall, cutting off the bacteria from the rest of the body but not killing the bacteria off. Those strains enter a latent period and if the immune system is weakens, the bacteria will break out and infect the rest of the body. In strains that work with the immune system, vaccines become useless because they are meant to boost the immune system, which in turn proliferates the bacteria.
In 1986, a mysterious outbreak of tuberculosis in New York led to more research on the microbe. This strain of tuberculosis spread quickly and was harder to treat than in past outbreaks. Eventually it made its way to San Francisco where tuberculosis experts made a startling discovery. It was originally thought that tuberculosis was only a part of one family but in reality there are six family strains of the bacteria. The strain that was spreading around San Francisco was a younger strain and DNA sequencing of those infected showed it was the exact same strain. This meant the latency period was short and little genetic change occurred which was unusual based on past tuberculosis findings.
With advancement in genome sequencing, researchers were able to locate the origin of the six families of tuberculosis. They found Africa was the only place to house all six families at some point. Yet the Euro-American family strain is more widespread. The Beijing strain, which was identified in the New York outbreak, was quickly spreading around the world. Yet an interesting discovery of tuberculosis is that in order to survive, mutations in housekeeping genes had to be minimal. This is generally counterintuitive for viruses and bacteria that want to evade the immune system.
New information about tuberculosis threatens to overcome current treatments and control methods. While social conditions, such as crowded housing and poor air quality, remain a factor in the spread of tuberculosis; other factors play a role as well. HIV and diabetes promote tuberculosis infections and help manipulate the immune system to enhance the transmission and activation. The original vaccine, which used a closely related bacterium, may actually be responsible for the proliferation of the more deadly tuberculosis strains. Further research of tuberculosis requires using new tuberculosis strains to be tested on and a critical understanding of tuberculosis’s family tree.